Weather is probably a major factor when you plan your trip to Osaka, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually August and July, with an average temperature of 25°C, while the coldest months are January and February, with an average of 10°C. The rainiest months in Osaka are June, July, October and September, with each month seeing an average of 283 mm of rainfall.